Light UI
Check dark outlines and shadows.
Browser demo · real VP8 Alpha export
One transparent animation.
Three real page backgrounds.
This is the same 4-second, 512 × 512 character file placed directly over light, dark, and gradient UI. No checkerboard is baked into the video.
WebMVP8 Alpha24 fps4.00 seconds
Dark UI
Check pale spill and soft edges.
Gradient hero
Confirm that the page shows through.
Playback starts only after you press Play. If your system requests reduced motion, the static PNG remains the default.
Use the exact files
Inspect the example in your own browser
Download the source package or open the files directly. The PNG is a static baseline; the WebM carries the animated Alpha channel.